campaigning in iowa, paul ryan fired back. >> vice president biden just today said that the middle class over the last four years has been, quote, buried. we agree. that means we need to stop digging by electing mitt romney the next president of the united states. >> reporter: later, the vice president did some damage control, clarifying his remarks. >> the middle class was buried by the policies of romney and that ryan supported. >> reporter: 24 hours before the start time of tonight's debate late tuesday, conservatives began circulating a 2007 speech by then candidate obama speaking to an african-american audience about victims of hurricane katrina. fox news host sean hannity prominently featured the video as a gotcha moment. >> it contains some of the most divisive class warfare and racially charged rhetoric ever used by barack obama. >> reporter: nbc, along with several other media outlets, covered the same speech at the time. mr. obama spoke at length about the hurricane response. >> people asked me whether they thought race was the reason the response was so slow. i said, well, no,